Floor plywood thickness

[Jey]

Hello everyone.

Quick backstory,

Water Damaged trailer-previous owners installed new plywood over rotting water damaged floor-we tore everything back out- new floor bracing is in.

I?m pretty sure the original floor was 15/32 or 1/2?  but it was all so rotted that we couldn?t tell. I know the floor they put OVER the damaged floor was in fact 15/32


I laid a sheet of 15/32 over the new floor braces today and it felt pretty spongy.. like it wasn?t thick enough. The guy at Lowe?s went back and forth with me about how I need at least 3/4? for a floor. However.. it?s not going to fit under my walls or cabinets.

Maybe it felt spongy because it wasn?t braced down.. but it definitely felt thin. I don?t know what it?s supposed to be like since when I got the trailer it had two layers of flooring plus the tile over top of that. Granted the first layer of flooring was rotted it was still adding some type of support.

We did add more floor bracing than was originally in the trailer for more support but I?m just not sure if we should just suck it up and have a spongy feeling floor or if there?s a work around. The flooring we have going over top is only about 6mm thick

 

[Gizmo100]

Maybe this will work

https://www.google.com/shopping/product/928495309285926414?lsf=seller:8740,store:3262230417137846005&prds=oid:11275767115413996146&q=5/8%22+plywood&hl=en&ei=KgfnXK0qjZCwBa-fibAM&lsft=gclid:EAIaIQobChMIq7LKqMOy4gIV27bACh3SMwgaEAQYAyABEgJN9_D_BwE,gclsrc:aw.ds

It's almost 5/8" which is the minimum I would use on a floor.

 

[Gods Country]

It's difficult to alleviate that spongy feeling because in all likelihood the original floor was laminated (glued) to the insulation and bottom board creating a stronger ply that's difficult to replicate.  The original was probably 1/4" luan.  1/2" is pretty thick for a trailer.  If you want to stay with the 1/2 inch I would add additional treated supports. 

Also be suspicious of the bottom board or other structural elements if the floor seems spongy with new flooring.  Typically when the flooring rots it's far deeper than you may suspect.

 

[Jey]

It's difficult to alleviate that spongy feeling because in all likelihood the original floor was laminated (glued) to the insulation and bottom board creating a stronger ply that's difficult to replicate.  The original was probably 1/4" luan.  1/2" is pretty thick for a trailer.  If you want to stay with the 1/2 inch I would add additional treated supports. 

Also be suspicious of the bottom board or other structural elements if the floor seems spongy with new flooring.  Typically when the flooring rots it's far deeper than you may suspect.

The flooring has been removed down to the plastic underbelly of the trailer. There wasn?t anything worth saving unfortunately so we had to strip it all out completely. Quite the process but starting fresh!

 

[SpencerPJ]

I would think 1/2" was enough.  What would help a bunch is if you put a little, 'liquid nails' on each floor brace prior to placing the sheet of floor on them.  When it is screwed together and all dries, it will be much stronger than just laying it down and stepping on it.

 

[Gods Country]

The flooring has been removed down to the plastic underbelly of the trailer. There wasn?t anything worth saving unfortunately so we had to strip it all out completely. Quite the process but starting fresh!

So the trailer is currently gutted including cabinets, etc, etc?

If that is the case then I would use 1/2 treated plywood on the bottom, treated 2x4's as needed to stiffen the floor. Add the top flooring using whatever is adequate.  Insulate in between with foam panels.  Glue and screw together.  You may still have a few soft spots, but at that point is will be
aesthetic.  Without seeing pics it's difficult to add much else.

 

[cic317]

There are 2  brands you can try , Sturdi floor or Avantech, 1 is plywood other is  an OSB product but much stiffer than typical plywood
These would be the best bet if you cant add additional bracing

 

[Jey]

So the trailer is currently gutted including cabinets, etc, etc?

If that is the case then I would use 1/2 treated plywood on the bottom, treated 2x4's as needed to stiffen the floor. Add the top flooring using whatever is adequate.  Insulate in between with foam panels.  Glue and screw together.  You may still have a few soft spots, but at that point is will be
aesthetic.  Without seeing pics it's difficult to add much else.

I was originally going to use PT plywood but Treated plywood weighs roughly 20lbs more per 4x8 sheet than non treated which would give me 80lbs+ extra by the time I put all the pieces in.


I?ve attached a photo of the current messy state of the floor.

 

[cic317]

Pressure treated plywood is shipped wet, take quite a while to dry & you need to used stainless or double hot dipped fasteners or the fasteners will react w/ chemical preservatives & rot. It also has lots of nasty chemicals, makes for a unhealthy air in an enclosed trailer, better off with Advan tech osb. It can be left exposed to rain for 300 days without degrading. Probably more than your trailer will ever see... Or at least hopefully

 

[grashley]

WHAT MESS??  That looks really great and done properly.  As others have said, glue and screw your choice of underlayment.  You are well on your way!

 

[Jey]

WHAT MESS??  That looks really great and done properly.  As others have said, glue and screw your choice of underlayment.  You are well on your way!

Lol I was referring to the yellow spray foam all over the place. I?ve used the foam in a can stuff and thought I was mature enough to use the foam gun and ?pro cans? this time. the very first day I was having to rinse my arms with olive oil and mineral spirits trying to get foam off my skin because I got it everywhere. But thank you for the kind words!

 

[Jey]

Okay I went to Lowe?s & Home Depot today. I checked out advantech 5/8 sheets and man they were just so much heavier than the 19/32 sheets we were looking at so we decided to go with the 19/32

Got it home and low and behold.. it won?t fit under the walls. Some sections it will but in others it would tear up the walls trying to hammer them into place.


So the new plan is to lay the 1/2 and secure it properly. If it still feels soft I?m thinking about, Depending on weight,  purchasing some 1/4 sheets and laying over top of the 1/2 and cutting it around the walls. .


Now to figure out why to do with this $28 sheet of 19/32 I can?t use!

 

[SpencerPJ]

Now to figure out why to do with this $28 sheet of 19/32 I can?t use!

If you didn't saw on it, return it.  The stuff I've seen returned....

 

[grashley]

Another option may be to sand the edge down that extra 5/32 and use what you have.  You get the thicker floor AND it fits under the wall.

 

[magothy1]

If you could get the use of a belt sander with a sort of coarse grit that idea of sanding the edge might be a good way to go.  Looks like you've got a good job going. The glue and screw method will stiffen things up and not dislodge things with hammering. Thinking in terms of going down the road, bumps, vibration, etc, screw and glue would be way better than nailing. The Advantech is very good material, but it's heavy.